title: [Haemorrhage in arteriovenous malformations of the brain following radiosurgery: the importance of the latency period].
abstract: BACKGROUND
  Arteriovenous malformations are abnormal communications between arteries and veins. Treatment can consist in surgery, embolisation and/or radiosurgery.
  
  
  OBJECTIVE
  To assess the influence of radiosurgery on the risk of bleeding and related factors.
  
  
  METHODS
  Retrospective study of 79 patients who were treated with a 6 MV linear accelerator. Clinical, morphological and dosimetric parameters were collected and a statistical analysis was performed to investigate their relationship with bleeding during the latency period.
  
  
  RESULTS
  The mean age was 33.7 years, and 56% of patients were females. The mean volume was 6.16 cm(3). Bleeding occurred before treatment in 52.6% of cases. Altogether 25% had been embolised and 7.6% had been treated earlier using radiosurgery. Six patients suffered a haemorrhage after treatment. Bleeding occurred in 21% of those who had undergone embolisation versus 3.6% in non-embolised individuals (p < 0.02). Bleeding occurred in 33.3% of those who had been treated radiosurgically on more than one occasion, and only 5.7% if they were treated just once (p = 0.02). Bleeding took place in 28.6% of lesions above 10 cm(3) and in 3.2% when they were smaller (p < 0.01). Bleeding occurred in 16.1% of patients if they received less than 17 Gy, and in 2.22% if they received 17 or more (p < 0.01). All haemorrhages took place in treatments with more than one isocentre (p < 0.01) and with a higher homogeneity index (p < 0.01).
  
  
  CONCLUSIONS
  Radiosurgery does not modify the risk of bleeding. The factors associated to higher percentages of bleeding are also related to poorer closure outcomes and longer latency periods.
authors.affiliation: Complejo Hospitalario Universitario de Vigo (CHUVI), Vigo, Pontevedra, España. pilirois@hotmail.com
authors.forename: P
authors.initials: P
authors.lastname: Varela-Rois
authors.forename: P
authors.initials: P
authors.lastname: Martínez-Cueto
authors.forename: A
authors.initials: A
authors.lastname: López-Medina
authors.forename: M
authors.initials: M
authors.lastname: Caeiro-Muñoz
authors.forename: F
authors.initials: F
authors.lastname: Salvador-Gómez
authors.forename: V
authors.initials: V
authors.lastname: Muñoz-Garzón
authors.forename: J M
authors.initials: JM
authors.lastname: Otero-Vich
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D004621:Embolization, Therapeutic; D005260:Female; D006470:Hemorrhage / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000150:complications* / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010315:Particle Accelerators; D016634:Radiosurgery / Q000009:adverse effects*; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult